Papermaking machine



April 969 R. w. RUSSELL ETAL 3,

PAPERMAKING MACHINE Sheet of4 Filed Oct. 5, 1966 April 1969 R. w. RUSSELL ETAL 3,440,137

PAPERMAKING MACHINE Filed Oct. 5, 1966 Sheet 2 0f 4 April 1969 R. w. RUSSELL ETAL 3,440,137

PAPERMAKING MACHINE Filed Oct. 5,1966 Sheet 3 of 4 April 1969 R. w. RUSSELL ETAL 3,440,137

PAPERMAKING MACHINE Filed Oct. 5, 1966 Sheet 4 of 4 United States Patent Office 3,440,137 Patented Apr. 22, 1969 3,440,137 PAPERMAKIN G MACHINE Roger W. Russel], Appleton, and Doyle L. Strong, Ni-

agara, Wis., assignors to Kimberly-Clark Corporation, Neenah, Wis., a corporation of Delaware Continuation-impart of application Ser. No. 346,699, Feb. 24, 1964. This application Oct. 5, 1966, Ser. No. 584,400

Int. Cl. D21f 2/00; B65h 17/00 US. Cl. 162306 Claims ABSTRACT OF THE DISCLOSURE A papermaking machine including a forming fabric on which paper stock is deposited for dewatering, a felt having a line of contact with the forming fabric onto which the resulting paper web transfers and a vibrator device for vibrating either the fabric or felt adjacent to the line of transfer for improving the paper web couching action from the fabric to the felt.

This application is a continuation-in-part of our copending application, Ser. No. 346,699, filed Feb. 24, 1964, now abandoned, for Papermaking Machine.

Our invention relates to papermaking machines, and, more particularly, the invention relates to apparatus and methods for couching paper web from the endless web forming screen of a Fourdrinier papermaking machine.

It is an object of the present invention to provide an improved method and apparatus for couching a paper web from the Fourdrinier wire to the felt of a papermaking machine by means of which the web may be removed from the wire with a more perfect transfer and with less fiber remaining on the wire than would be otherwise possible and by means of which the transfer may be obtained using less moisture in the sheet and using less moisture in the pickup felt than would otherwise be possible.

In practicing the invention, we have found that if the pickup felt is vibrated in the vicinity of the line of transfer of the web to the pickup felt, such improved transfer of the web to the felt is obtained; and the invention, therefore, contemplates that the felt shall be so vibrated and contemplates the use of vibrator mechanism for acting on the felt in this manner.

Alternatively, the Fourdrinier wire may be vibrated in lieu of the felt with the same effective transfer of the paper web to the felt at the couch line. In order to obtain the benefits of the invention, it is only necessary that there be relative vibration of the wire and felt at the line of coach of the wire and felt at the outgoing side of the nip between the wire and felt.

The invention consists of the novel constructions, arrangements, devices and methods to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as will be apparent from the following description of preferred forms of the invention and method for carrying out the invention, illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic elevational view of a Fourdrinier type papermaking machine embodying the principles of the invention and including a rotatable vibrator device for the pickup felt of the machine;

FIG. 2 is a side elevational view of the rotatable vibrator device;

FIG. 3 is an end view of the vibrator device;

FIG. 4 is a fragmentary plan view of a Fourdrinier wire in connection with which the vibrator device may well be used;

FIGS. 5 and 6 are sectional views taken on lines 55 and 66, respectively, of FIG. 4; and

FIGS. 7 to 14 are diagrammatic illustrations of modified couching arrangements using the vibrator device or a modified form of the vibrator device for increasing the couching eificiency.

Like characters of reference designate like parts in the several views.

Referring now to FIG. 1, the illustrated papermaking machine may be seen to comprise an endless Fourdrinier wire or screen 10 disposed over a breast roll 11, a couch roll 12, and turning rolls 13 and 14. A vacuum forming box 15 may be provided beneath the horizontal pass of the wire 10 between the rolls 11 and 12, and a paper stock inlet 16 of any suitable type is provided for discharging paper stock onto the wire 10 in the vicinity of the breast roll 11. In accordance with conventional practice, a vacuum producing device (not shown) is connected to the box 15 and may, for example, apply a vacuum of one inch of mercury to the box 15.

An endless felt 17 is disposed about a pickup roll 18, a pressure roll 19, and turning rolls 20, 21 and 22. A vacuum box 23 is provided to be effective on the inner surface of the felt 17, and a water shower 24 is provided for showering the outer surface of the felt 17.

The roll 19 has a pressure nip with a steam heated Yankee drier drum 25, and the web 26 that is formed by the papermaking machine travels to a conventional winder 27 over suitable guide rolls, such as the roll 28. The wire 10 travels in the direction indicated by the arrow A; the felt travels in the direction indicated by the arrow B, and the Yankee drier 25 revolves in the direction indicated by the arrow C.

A vibrator device 29 is provided, according to the invention, to be effective on the felt 17, particularly on the pass of the felt in the direction of travel B from the pickup roll 18, and particularly between the vacuum box 23 and the pickup roll 18. Referring to FIGS. 2 and 3, the vibrator device as illustrated comprises a shaft 30 having a pair of discs 31 and 32 fixed thereon. Three rods 33, 34 and 35 extend between the discs 31 and 32. The rods 33, 34 and 35 are equally spaced from each other and are equally spaced from the center of the shaft 30, as shown. A driving motor 36 of conventional construction is provided for driving the shaft 30 and thereby rotating the discs 31 and 32 and the rods 33, 34 and 35 about the center of the shaft 30. The shaft 30 is mounted by any suitable bearings (not shown) with respect to the felt 17 so that each of the rods 33, 34 and 35 makes contact with the felt 17 as the shaft 30 and discs 31 and 32 rotate thereby effectively pounding, striking and vibrating the felt 17 each time one of the rods 33, 34 and 35 makes contact with the felt 17.

The felt 17 may be of any suitable conventional type for picking up a paper web from the Fourdrinier wire 10 and transferring it to the dried 25. The Fourdrinier wire or screen 10 may also be of any conventional type, and the vibrator device 29 improves pickup of the paper web 26 from the wire, as will be more fully described hereinafter. The Fourdrinier screen illustrated in FIGS. 4, 5 and 6 is of a type that has long, high wire knuckles extending in the cross machine direction, and this Fourdrinier screen is disclosed and claimed in the application of Harold H. Heller and John B. Graham, Ser. No. 28,291, filed June 23, 1960. This Fourdrinier screen, due to its long, high transverse knuckles has the capacity of forming a tissue web that has an unusually large number of its fibers extending in the cross machine direction, so that the tissue is particularly strong in this direction. With such a screen, the paper web has an unusually great ailinity for the screen, and the present invention is particularly effective in couching off the formed paper web from such a screen.

Referring to FIGS. 4, and 6, the illustrated Fourdrinier screen may be seen to comprise a plurality of warp wires 37 extending in the machine direction, that is, in the direction of travel of the screen indicated by the arrow A, and a plurality of transversely extending shute wires 38 interwoven with the wires 37. The papermaking side of the screen is illustrated in FIG. 4; and it will be observed from FIG. 6, which is a sectional view from FIG. 4, that each of the shute wires 38 extend successively over a pair of warp wires 37 and thence under a single warp wire 37 looking on the screen from its papermaking side. Successive shute wires 38 extend under adjacent single warp wires 37 so that a semi-twill weave is formed.

The knuckles 39 of the transverse wires 38 on the paperrnaking side of the screen are higher than the knuckles 40 of the longitudinal wires 37, and the longitudinal wires 37 are spaced a greater distance apart than are the transverse wires 38. In this construction, therefore, the transversely extending wire knuckles 39 are both higher and longer than the longitudinal wire knuckles 40 on the papermaking side of the screen, and the construction also provides openings 41 between the wires which are longer transversely of the screen than longitudinally of the screen. The result of this construction is that certain paper fibers 42 tend to be moved from longitudinal positions of the screen to extend transversely of the screen, since a great flow of white water through the screen takes place parallel with the long, high transverse knuckles 39, and the fibers tend to flow along and be directed in the same direction as the flow of white water. As is well known, with ordinary Fourdrinier screens, more paper fibers lie in the machine direction than in the cross machine direction; and the major lie of the redirected paper fibers 42 mostly in a cross machine direction is just opposite to the usual lie of paper fibers produced by a Fourdrinier machine. In view of the fact that the fibers 42 do lie along the long, high knuckles 39, they are embedded farther into the wire and draped through the openings 41 to a greater extent than if a conventional Fourdrinier screen is used; and the resulting web is accordingly couched from the screen with more difficulty.

The Fourdrinier screen illustrated in FIGS. 4, 5 and 6, may instead be constructed to be endless in the direction indicated by arrow B, so that the Fourdrinier screen is run in this direction on the machine. Using the screen in this manner results in a greater number of fibers extending in the machine direction than would otherwise be the case and results in a web that is stronger longitudinally than otherwise. The paper fibers in this case also extend farther into the wire and drape through the openings in the wire to a greater extent than if a conventional Fourdrinier screen is used, and in this case the resulting web is couched from the screen with more difficulty.

In operation of the machine, the paper stock from the inlet 16 is deposited onto the screen 10, and white water from the paper stock drains through the screen and into the vacuum forming box 15, so that a resulting sheet 26 is formed on the screen 10. The sheet transfers from the wire 10 onto the lower surface of the felt 17 at the nip between the rolls 18 and 12. The felt 17 functions to further dewater the web as the web is carried toward the Yankee drier 25, and the web transfers onto the drier 25 at the nip of the pressure roll 19 and the drier 25. The web is dried on the drum 25 and is removed from the drum and is wound into rolls by means of the winder 27.

We have found that a more complete transfer of the paper web 26 is obtained from the screen 10 onto the felt 17 using the vibrator device 29 than without the use of the device 29. The rods 33, 34 and 35 each make impact with the inside surface of the felt 17 for each revolution of the shaft 30 and plates 31 and 32; and, therefore, with the three rods 33, 34 and 35, three impacts are thus given to the felt 17 for each revolution of the shaft 30 and plates 31 and 32. The shaft 30 and the other connected parts of the vibrator device may be rotated in either direction in order to produce these impacts on the felt 17. The vibrator device 29 may be moved toward or away from the pickup roll 18; however, we have found that it may well be located from two to six inches away from the nip between the rolls 12 and 18 with this improved effect on couching. The amount of impact of each of the rods 33, 34 and 35 may be changed while still obtaining the advantages of the invention; however, we have found that very effective couching is obtained with the rods deflecting the felt 17 inch to Mt inch, assuming that there is a l2-inch span, for example, between the vacuum box 23 and the pickup roll 18. The number of impacts per linear inch of travel of the felt 17 may also be changed within wide limits while still obtaining the advantages of the invention; however, we have found that 5 to 30 impacts per linear inch of felt travel are very effective. Lighter sheets apparently should have a greater number of impacts from the vibrator device 29 than heavier sheets. For example, a sheet having a dry basis weight of 10 to 15 pounds per 3,300 square feet transfers very well with 5 impacts per linear inch of felt travel, while sheets of a basis weight of 4 to 5 pounds per 3,300 square feet couched best with about 7 impacts per linear inch of felt travel.

As is well known in the papermaking art, better conching of a paper web from a Fourdrinier wire to a felt is obtained if the web at the line of transfer is maintained relatively wet or if the felt is maintained relatively wet. Using the vibrator 29 allows the use of a drier sheet at the line of transfer to the felt and allows the use of a drier felt 17, which may be obtained by decreasing the amount of water that is applied to the felt from the shower 24. Some paper furnishes tend to stick to the Fourdrinier wire more than others, and we have found that the use of the vibrator device 29 makes a definite improvement in the degree of couching that is obtained using such difficult couching furnishes. As has been above pointed out, the Fourdrinier screen illustrated in FIGS. 4, 5 and 6 provides a web that is couched with difficulty from the screen due to the fact that the fibers tend to lie along the high, long transverse knuckles 39; and we have found that couching from this type of Fourdrinier screen is much more effective utilizing the vibrator device 29 than without the use of the device 29.

As will be observed from FIG. 1, the pickup roll 18 is disposed nearly directly above the couch roll 12. The vibrator of the invention is effective also in many other different types of couching arrangements in which the vibrator device is located close to the line of contact of the felt and screen. A different pickup arrangement, in which a vibrator 29a similar to the vibrator 29 is effective, is shown in FIG. 7. 'In this arrangement, a Fourdrinier screen 10a passes around a couch roll 12a. A felt 17a is in light contact with the screen 10a passing over the roll 12a, and there is an angle x (which may be about 41, for example) between the incoming passes of the screen 10a and felt 17a. The felt 17a lies across the roll 12a in substantially a fiat plane, and the vibrator 29a is effective on the pass of the felt leaving the couch roll 12a. With this arrangement, it was found that with some furnishes, couching with this arrangement was possible only while using the vibrator device 29a.

A couching arrangement providing a tighter contact between the felt and screen is illustrated in FIG. 8. In this arrangement, the Fourdrinier screen 10b passes around the couch roll 12b, and the felt 17b lies over the couch roll 12b and the portion of the screen 10b carried by the couch roll; and the felt has its direction of movement changed by the couch roll. A vibrator device 29b is effective on the felt 17b as it leaves the couch roll 12b; and, with this arrangement also, the vibrator device materially improves couching. The felt 17b leaves the couch roll 12b at about the same angle with respect to vertical as the felt 17a leaves the couch roll 12a; but, in the FIG. 8 arrangement, the angle y between the incoming passes of the Fourdrinier screen and felt is less than the angle x and may, for example, be about 34.

The couching arrangement illustrated in FIG. 9 is a so-called free wire pickup. The Fourdrinier screen 100 in this arrangement passes over turning rolls 43 and 44 which are so disposed that there is a pass of the screen 10c between the rolls that is inclined downwardly. A pickup roll 18c holds the felt 17c in contact at a slight pressure with the pass of the screen between the rolls 43 and 44. The vibrator device 290, similar to the device 29, is provided adjacent the pickup roll 18c along the pass of the felt 170 as it leaves the pickup roll 18c. With this arrangement, couching of the paper web is materially bettered using the vibrator device 290.

The couching arrangement shown in FIG. 10 includes the couch roll 12d over which the Fourdrinier wire 10d passes. A pickup roll 118d holds the felt 170? in tight contact at the nip between the rolls 12d and 18d. A vibrator device 2 9d similar to the device 29* is provided adjacent the roll 18d along the pass of the felt 17d as it leaves the roll 18d. The vibrator 29d makes the pickup cleaner and more effective.

The couching arrangement illustrated in FIG. 11 utilizes a pickup roll 18:: holding the felt 17a in contact with a horizontal pass of the Fourdrinier wire 10c supported by the couch roll 12c. The roll 1*82 holds the felt 17e in contact with the screen 10a along a line which is just prior to the couch roll 12c. A vibrator device 29c, similar to the device 29, located adjacent to the roll 18e on the stretch of felt 17e leaving the roll 18e materially increases the couching efiiciency, causing more fibers to transfer to the felt 17c and a cleaner Fourdrinier screen, than without the use of the vibrator device.

All of the couching arrangements previously described utilize a vibrator device effective on the pass of the felt leaving its line of couch with the Fourdrinier wire. It is not necessary that the vibrator device be effective on this pass of the felt in order for the benefits of the invention to be realized. The vibrator device can instead be used on the pass of the Fourdrinier wire leaving the line of couch, it being only necessary that there be a relative vibration between the wire and the felt at this line. A vibrator device may also be positioned on the wire at the other or inrunning side of the couch or pickup line, and suflicient vibration will be transmitted through the wire, which has substantial rigidity, to the couch line offrunning side, at which the vibration is particularly effective for the intended purpose, to materially better the pickup of the web from the wire onto the felt. Alternatively, a vibrator device may be positioned on the pass of the felt approaching the couch line, and suflicient vibration for the intended purpose may be transmitted through the felt, although the felt is much more flexible than the wire, assuming that the felt is so disposed that it makes little bend in passing across the couch line. In all of the instances, including those disclosed in FIGS. 1 and 7 to 11, the vibrator device may be positioned as close as possible to the couch line as the parts of the machine will permit, or the vibrator device may be positioned as far as desired from the couch line but between the couch line and the next adjacent roll supporting either the wire or felt, but in the latter cases the amplitude of vibration must probably be increased to provide the substantial relative vibration between the wire and felt at the couch line on the offrunning side of this line to secure the best results.

The couching arrangement illustrated in FIG. 12 is quite similar to that illustrated in FIG. 11 except that the vibrator device 29 is positioned to be effective on the pass of the wire leaving the couch line rather than on the pass of the felt leaving the couch line. The FIG. 12. arrangement includes a breast roll l11f and a couch roll 12f supporting the wire 10f. A pickup roll 18 and a pressure roll 19 support the felt 17 The roll 18 holds the felt 17 in contact with the wire 10f, depressing the wire 10 to a slight extent; and the pressure roll 19f holds the felt 17 f in forceful contact with the drier 25 The vibrator device 29 is positioned beneath the wire 10 and between the rolls 18 and 12 and is thus effective on the pass of the wire 10 leaving the pickup roll 18 subsequent to the couch line on the periphery of the pickup roll 18]. The vibrator device 29 is substantially the same as the vibrator devices 29a to 29c except that the device 29 comprises an elongated tubular structure having a triangular cross section in lieu of the rods 3'3. As each of the apexes of the triangular structure contacts the wire 10 it produces a vibration of the wire 10 and this vibration is transmitted through the wire 10 back to the couch line on the periphery of the roll 18f on the offrunning side of the couch line.

The couching arrangement illustrated in FIG. 13 is substantially the same as that illustrated in FIG. 12, except that a vibrator device 29g is effective on the Fourdrinier wire prior to the couch line and on the inrunning side of the couch line. The FIG. 13 arrangement comprises a breast roll 11g and a couch roll 12g supporting the Fourdrinier wire 10g. The felt 17g of the machine is supported by means of a pickup roll 18g and a pressure roll 19g, the pressure roll holding the felt 17g in contact with the drier 25g. The vibrator device 29g is effective on the under surface of the wire 10g on the pass of the wire 10g between the breast roll 11g and the pickup roll 18g. The line of couch of the wire 10g and felt 17g is underneath the pickup roll 18g, and sufficient vibration is transmitted through the wire 10g to the offrunning side of the pickup or couch line so that there is a material improvement in the pickup of the web from the wire 10g to the felt 17g although the pickup is not as complete as in the case in which a vibrator is disposed on either the wire or felt subsequent to the pickup or couch line, due to the fact that the pickup roll 18g tends to dampen out the vibrations produced by the vibrator device 29g.

The couching arrangement illustrated in FIG. 14 is quite similar to the couching arrangement illustrated in FIG. 7 except that the vibrator device is positioned on the pass of the felt prior to the couch or pickup line of the felt and Fourdrinier wire, rather than on the pass of the felt subsequent to this line. The FIG. 14 arrangement comprises a breast roll 11h and a couch roll 12h supporting the Fourdrinier wire 10h. The felt 17h is supported by means of two rolls 37 and 38 so positioned with respect to the couch roll 12h that the pass of the felt 17h between the rolls 37 and 38 is substantially in a flat plane with the felt having a light or kissing contact with the wire 10h on the periphery of the couch roll 12h. The vibrator device 29h is positioned on the pass of the felt 17h between the rolls 37 and 12h, and sufficient vibration is transmitted through the felt 17h to the offrunning side of the felt at its line of contact with the wire, due to the fact that the felt 17h is in a substantially flat plane between the rolls 37 and 38, so that pickup of the web from the wire to the felt is materially improved.

Although the efiiciency of couching and the degree of transfer of fiber to the felt from the Fourdrinier screens have by experiment proved to be materially bettered using the vibrator device of the invention, the exact theory for the cause of such betterment is not known; however, any one or all of the following theories may be the basis for this result.

It is well known in Fourdrinier papermaking machine operation that a pickup gelt picks up the web better if it iskept in relatively wet condition and if there is substantial water on the surface of the felt, so that the surface tension of the water is effective to draw off the fibers of the web from the Fourdrinier screen. It is believed that the vibration due to the vibrator devices 29, 29a, etc. may tend to provide more water on the surface of the pickup felt by driving the water from inside the felt onto the outside felt surface. Possibly the vibration breaks up the water into small droplets from inside the felt that collect on the surface of the felt. Since the felt, in accordance with this theory, has more water on its surface due to the vibration, the felt therefore picks up the web more efficiently, since, as above mentioned, a wet felt in ordinary papermaking picks up much better than a drier felt. The use of the vibrator device of the invention thus allows the use of a felt which carries less moisture than would otherwise be possible.

Another theory that may be used to explain the effective couching using our vibrator devices is that the rate of movement of the felt and wire apart is increased by the beating that our vibrator devices give to the felt. The vibrations of the felt are essentially normal to the felt; and, therefore, during the vibrations, the felt and wire move apart, not only due to the angle between the separating passes of the felt and wire as they move apart, but also due to the vibration of the felt normal to its direction of movement. This action may be compared to the action of a piece of plywood, for example, being pulled from a puddle of slurry in which some of the slurry will be pulled up from the puddle if the plywood is pulled up rapidly from the puddle, but substantially none of the slurry will be disturbed if the plywood is pulled up gradually. The adhesive force of the felt with respect to the sheet is apparently increased, due to increased surface tension effects, as the velocity of separating movement of the screen and felt is increased.

The third theory, which may be used to explain the increased couching effect provided by our vibrator devices, concerns the vacuum effects that are produced at the line of separation of the felt and Fourdrinier screen. It has previously been theorized in connection with ordinary couching arrangements that when the felt and wire are put under substantial pressure at their line of separation, the compression of the felt in the nip results in a felt that is substantially 100 percent saturated in the nip. It is assumed that the felt has previously been carrying a substantial amount of water, being about 50 percent saturated with water, for example, which is about the usual case. The voids are squeezed out of the felt in the nip due to the pressure at the nip, and the felt in leaving the screen can be expected to expand into its original thickness, and the voids that were originally in the felt will reappear therein and will tend to fill up with air. The air sucking into these voids thus creates a slight vacuum between the felt and the sheet which causes the sheet to adhere to the felt.

By vibrating the felt at a relatively fast speed, it is believed that there is a tendency to provide a void between the sheet and the felt at the line at which the felt leaves the screen, and the air rushing up beneath the web thus pushes the web against the felt and causes it to adhere to the felt.

Another theory that may be utilized to explain the effectiveness of the vibrator devices 29, etc., is based on the theory of couching set forth in Baggalley et a1. Patent 2,990,013, which is to the effect that, if water is released from the web toward the wire, it forms a film between the web and wire and that this water facilitates clean removal of the web from the wire provided that this removal is effected before the water can reabsorb into the web. Utilizing the vibrator devices 29, etc., may cause water from the web, as the web leaves the wire, to be directed by the vibration of the web and felt to the wire and thus form such a film on the wire facilitating clean removal of the web from the wire.

A theory in connection particularly with the long, high knuckle screen illustrated in FIGS. 4, and 6 is that perhaps, due to the vibration of the felt, the felt is driven down farther into the interstices of the screen and around the knuckles of the wire, particularly around the high knuckles 39 of the screen illustrated in FIGS. 4, 5 and 6, so that the felt thereby comes into contact with more of the fibers and causes them to adhere to the felt due to the high density of the felt as compared to the screen, whereby more of the fibers transfer onto the felt. As has been previously mentioned, the fibers of a paper web tend to embed themselves quite deeply in a high knuckle wire as illustrated in FIGS. 4, 5 and 6.

Therefore, in brief, our invention teaches that, by producing a relative vibration between the wire and felt at the couch nip, couching can be improved.

The couching arrangements of the invention, including the vibrators 29, 29a, etc., are effective with different types of Fourdrinier screens; however, the effectiveness of the pickup arrangements of the invention is particularly noticed in connection with Fourdrinier screens in which the webs tend to adhere and interlock by means of their fibers with the screens, such as the Fourdrinier screen illustrated in FIGS. 4, 5 and 6 with the long, high knuckles 39. The pickup arrangements of the invention are particularly effective also in connection with new felts which have not been broken in, and it has been noticed that the vibrators of the invention have about the same beneficial effect as the substitution of a much softer, thicker felt for a relatively thin, hard felt having poor pickup qualities, insofar as clean removal of the web from the Fourdrinier screen is concerned. Under couching conditions, which are poor for one reason or another, the poor couching without use of a vibrator can be improved to near perfect couching conditions using a vibrator according to the invention; and the difference in couching under the two conditions is definitely noticeable in that when the vibrator is not in use a considerable amount of fiber is left remaining on the Fourdrinier screen after the couch line, while when the vibrator is in use, practically all of the fibers are removed from the Fourdrinier screen and are transferred to the felt.

Our vibrator devices provide excellent couching even though the quality of the pickup felts is not at the desired best. Lost production time in breaking in new felts on a papermaking machine can, therefore, nearly be eliminated or at least reduced considerably. Utilizing our vibrator devices also allows a papermaking machine to be operated with less moisture in the paper web at its couch position on the Fourdrinier screen as well as with less moisture in the pickup felt itself; and, as a result, therefore, a sheet of lower total moisture content may be delivered to the steam heated drier of the paper machine. A reduction in the required drying capacity of the drier of a paper machine, or an increase in machine speed if no change is made in the capacity of the drier, can therefore be realized utilizing the felt vibrators of the invention.

Although we have illustrated rotary types of vibrators 29, 29a, etc., it will be appreciated that other conventional purely mechanical or electro-mechanical vibrator devices can instead be utilized, while still obtaining the advantageous results of the invention.

We wish it to be understood that the invention is not to be limited to the specific constructions, arrangements, devices and methods shown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. In a papermaking machine, a pair of endless belts, a plurality of rolls for supporting said belts in looped form so that the belts may travel about their respective rolls and have a line of contact with each other, one of said belts constituting a screen on which pulp is carried and is partly dewatered to form a continuous paper web and the other of said belts constituting a felt onto which the paper web transfers from said screen at said line of contact, and a vibrator device for causing vibration of said felt at the elf-running side of said line of contact.

2. In a papermaking machine, a pair of endless belts, a plurality of rolls for supporting said belts in looped form so that the belts may travel about their respective rolls and have a line of contact with each other, one of said belts constituting a screen on which pulp is carried and is partly dewatered to'form a continuous paper web and the other of said belts constituting a felt onto which the paper web transfers from said screen at said line of contact, and means for causing vibration of one of said belts at said line of contact on; the olfrunning side thereof for thereby facilitating clean removal of the web from said screen as it passes onto said felt, said vibration causing means comprising a rotary device having a plurality of spaced protrusionseach of which contacts and makes impact with said one belt as the device is rotated for thereby vibrating the belt.v

3. In a papermaking machine as set forth in claim 1, one of said rolls for supporting said screen having a nip with one of said rolls for supporting said felt to thereby provide said line of contact.

4. In a papermaking machine as set forth in claim 1, one of said rolls for supporting said felt being so positioned as to hold said felt in contact with an area of said screen located between two of said screen supporting rolls whereby to provide said line of contact on the area of the screen between said two last named rolls.

5. In a method of removing a paper web from an endless screen belt of a Fourdrinier papermaking machine which travels over a plurality of spaced rolls and carries the web in partly dewatered condition, the steps which comprise, running an endless traveling felt belt over a plurality of spaced rolls and in a line of contact with said screen belt whereby the paper web travels from said screen belt onto said felt belt at said line of contact, and causing vibration of one of said belts at said line of contact on the ofirunning side thereof for thereby facilitating clean removal of the web from said screen belt onto said felt belt, said one belt being vibrated with five to thirty vibrations per linear inch of travel.

References Cited UNITED STATES PATENTS 2,647,619 8/1953 Green 198--230 3,207,658 9/1965 Lamb .162203 DONALL H. SYLVESTER, Primary Examiner. A. c. H-ODGSON, Assistant Eicaminer.

, US. Cl. X.R. 226-5; 198-230 

